Subject: Re: Playing with SATA NCQ
From: Erik Slagter <erik@slagter.name>
To: Jeff Garzik <jgarzik@pobox.com>
Cc: linux-kernel@vger.kernel.org, linux-ide@vger.kernel.org,
       Jens Axboe <axboe@suse.de>
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Date: Sun, 29 May 2005 19:23:52 +0200
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On Sun, 2005-05-29 at 12:59 -0400, Jeff Garzik wrote:

> >>Nope.  ata_piix does not support NCQ (because the h/w doesn't support).
> > If I understand this correctly: NCQ does not work on ICH7 in native mode
> > (using ata_piix) because in this mode there is no NCQ available, right?
> 
> To be more specific, there are these modes:
> 
> 	legacy mode		no NCQ
> 	combined mode		no NCQ
> 	native mode		no NCQ
> 	AHCI mode		NCQ

Thx.

> > My question was if there is a fundamental reason why the AHCI mode of
> > the ICH6/7 must be enabled by the BIOS, is there a reason why the kernel
> > doesn't do it, or can't do it?
> 
> The BIOS sets up PCI resources necessary to use AHCI mode.

Ok. So there's absolutely no way to do that afterwards? It'd really be a
pity :-(

On the same subject: is there a reason why ICH6 gets "BAR0-3 ignored"
and always gets the legacy i/o ports and IRQ's assigned? I'd say there
is absolutely no need to be compatible in this way, the PCI code can
assign the IRQ and I/O ports as with any other PCI device?
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